Written By Gopal Krishna on Saturday, October 20, 2007 | 3:03 AM

In an effort to save Yamuna, Delhi Pollution Control Committee (DPCC) should learn from the Assam Pollution Control Board that has issued a directive for retrieval of Durga idol structures after immersion in the Brahmaputra. This was needed to lessen pollution load due to immersion.

The idol immersion in water bodies is the social ritual followed immediately after the Dushehra celebrations. At the end of the festival, the idols are taken into processions to various ghats of River Yamuna for immersion in river water. The immersion of worship idols in Yamuna River after Dushehra is done from upstream Wazirabad to downstream Okhla barrage at Ramghat, ISBT and Okhla in Delhi stretch of River Yamuna.

The idols are made up of plaster of paris, clay, and cloth supported by small iron rods, and are coloured with different types of paint such as varnish and watercolours. When immersed, these coloured chemicals dissolve slowly leading to significant alteration in the water quality.

Thousands of idols of various sizes reaching heights up to 45 to 50 feet are immersed in the water bodies at the immersion sites. Magnesium, molybdenum and silicon concentrations also increases significantly in the lake water after the idol immersion that increases the hardness of water. Over the years, the average concentration of heavy metals, especially arsenic, lead and mercury has also increased considerably in the lake water compared to the specifications of highest desirable limits as set by BIS and ICMR standards.

The concentration of arsenic, a noxious trace element, has increases several fold in the lake water after the idol immersion, compared to its BIS and ICMR standards. Excess of this element causes skin diseases. Lead and mercury, the potentially obnoxious heavy metals increases many-fold in the water due to the idol immersion. The heavy metals are known to be persistent in the aquatic environment, and gradually accumulate and magnify through the process known as bioaccumulation and biomagnification, while they move up in the food chain.

Thus, lead and mercury may magnify in their concentrations at different trophic levels, including in fishes and birds inhabiting the lake, which finally reach the humans through food. Organic compounds of mercury, for example methyl mercury when it enters the human body, concentrates in the brain and destroys the brain cells, damaging the central nervous system, and also causes corrosion and ulceration of the digestive tract. Thus, people consuming contaminated fish caught from the lake over a period of time may get afflicted with mercury poisoning. Therefore, it is suggested that the authorities looking into the environmental protection of the lake need to take necessary steps.It has been established by studies that these idols have impact on aquatic environment during immersion.Impact of Various Items on Aquatic Environment during Immersion of Idols S. No. Items contributed by idols immersion Impact on Aquatic Environment 1. Clay/Plaster of Paris Increase dissolved solids, suspended solids in water, contribute metals, sludge 2. Decoration material viz. clothes, polish, paint, ornaments cosmetic items etc. Contributes suspended matter, trace metals (Zinc, lead, iron, chromium, arsenic, mercury etc.) metalloids and various organic and inorganic matter, oil & grease etc. 3. Flowers, Garlands, oily substance Increase floating suspended matter organic contamination, oil & grease and various organic and inorganic matter 4. Bamboo sticks, Beauty articles Big pieces got collected and recycled while small pieces remain floating in water or settled at the river bottom inhabiting river flow 5. Polythene bags/plastic items Contribute suspended, Settleable matter and hazardous material to water and chokes the aquatic life 6. Eatables, food items etc. Contributes oil and grease, organics to water bodies. The impact on water quality of river have been observed with respect to levels of conductivity, Total and Dissolved solids. Biochemical oxygen demand. River bed sludge analysis reflected elevated levels of trace metals viz. iron, arsenic and mercury. Based on the study of Central Pollution Control Board, the following suggestions were made to reduce the pollution load from idols immersion activities:- Areas may be earmarked for immersion and other related activities to prevent indiscriminate disposal and to help retrieval of recoverable materials.- Temporary confined pond near rive locations may be identified for immersion of idols and other worship material to prevent pollution of main river stream. The closed pond water may be disposed into Main River after settling, scavenging and treatment.- The offerings like flowers and leaves may be collected in separate containers or in pits for composting.- After immersion, the recyclable articles like Jari, Clothes, plastics, aluminium foil, wood and bamboo may be taken out from the water bodies. The civic authorities may engage agencies/persons for doing the job. - Environment friendly practices such as use of biodegradable dyes and paints may be encouraged. - Public should be made aware of adverse affects of idol immersion in river water. - Rag picker activities through which recyclable material is removed should be encouraged further to avoid the contamination of river water with floating materials like plastics, flowers, wooden structure etc.

DPCC should issue a directive similar to one given by Assam Pollution Control Board to protect Yamuna to lessen pollution loads under the provisions of the Water Act, 1974 and Environment Protection Act, 1986, to ensure that idol structures are collected from water bodies within 24 hours of immersion.